#region The MIT License
// The MIT License
// 
// Copyright (c) 2009 octalforty studios
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
#endregion
using System;
using System.ComponentModel.Composition;
using System.Diagnostics;

namespace octalforty.Componento.ComponentModel.Commands
{
    /// <summary>
    /// Standard implementation of the <see cref="ICommandResolverService"/>.
    /// </summary>
    [Export(typeof(ICommandResolverService))]
    public class CommandResolverService : ICommandResolverService
    {
        #region Private Fields
        private Lazy<ICommand, ICommandMetadata>[] commands;
        #endregion

        #region Public Properties
        /// <summary>
        /// Gets or sets a reference to the collection of <see cref="ICommand"/> objects
        /// with associated metadata.
        /// </summary>
        [ImportMany()]
        public Lazy<ICommand, ICommandMetadata>[] Commands
        {
            [DebuggerStepThrough]
            get { return commands; }
            [DebuggerStepThrough]
            set { commands = value; }
        }
        #endregion
        
        #region ICommandResolverService Members
        /// <summary>
        /// Returns a <see cref="ICommand"/> with name <paramref name="name"/> or <c>null</c> if no
        /// command with the given name is registered.
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public ICommand ResolveCommand(string name)
        {
            if(name == null) 
                throw new ArgumentNullException("name");

            if(Commands == null)
                return null;

            foreach(Lazy<ICommand, ICommandMetadata> command in Commands)
                if(string.Compare(command.Metadata.Name, name, StringComparison.CurrentCultureIgnoreCase) == 0)
                    return command.Value;

            return null;
        }
        #endregion
    }
}
